Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 302333

Area Forecast Discussion
National Weather Service Sioux Falls SD
633 PM CDT Fri Sep 30 2016

.SHORT TERM...(This evening through Saturday)
Issued at 303 PM CDT Fri Sep 30 2016

Main concerns tonight into Saturday will be the stratus working west
across Iowa. Suspect that this area of cloud cover will work west to
about the James Valley overnight, but should pause there, then
likely retreat east a bit during the day. Some spotty fog will again
be possible overnight with more high clouds and stratus the chance
of having any visibilities below a mile is lower. Model soundings
suggest that most of the area covered in stratus will have trouble
shaking it. Once mixing begins a small amount of CAPE shows up which
will likely allow additional cloud development through the
afternoon. This will hinder highs a bit so did lower them a bit in
southwest Minnesota and northwest Iowa, mainly to 66 to 69. West of
Interstate 29 highs should top out from 70 to 75. Lows will be a bit
warmer tonight, ranging from the upper 40s near the James Valley to
50 to 55 closer to Storm Lake and Spencer Iowa.

.LONG TERM...(Saturday night through Friday)
Issued at 303 PM CDT Fri Sep 30 2016

Stratus will likely continue to blanket the eastern half of the
region Saturday night into at least Sunday morning. Models suggest
that this layer will eventually mix out in the afternoon as south
southeast winds increase ahead of the next approaching weather
system. This should allow temperatures to recover nicely into the
70s. Warmest temperatures will be found across south central SD
where sunshine will be copious and warm air advection and winds will
be strongest, allowing highs near 80.

Large upper level low over the Intermountain West barrels eastward
into the northern and central Rockies Monday and Monday night.
Southerly winds increase further on Monday, becoming fairly windy
across the Plains on Monday. Winds look strongest west of I-29 with
gusts around 30 to 40 mph possible. Temperatures will again be
seasonally warm, improving a few degrees from Sunday.

Models coming into decent agreement with the timing and track of the
upcoming system. Surface low deepens over the high Plains Monday and
lifts northward into the western Dakotas Monday night into Tuesday.
Copious moisture advection in the warm sector will ignite showers
and thunderstorms beginning in south central and southeast South
Dakota Monday night, mainly after midnight. This precipitation band
shifts eastward on Tuesday, with thunderstorms becoming more
widespread by afternoon and evening. As the low lifts into North
Dakota and southern Manitoba, the precipitation band shifts east of
the region, placing us in the dry slot Wednesday and Wednesday
night. A few isolated/lingering showers may be possible during this
time, but it does look like the bulk of the wet weather will end
Wednesday. Temperatures cool with the arrival of the rainfall and in
the wake of the exiting system mid week. Highs are expected in the
60s and 70s Tuesday and Wednesday, but drop into the upper 50s to
mid 60s on Thursday and Friday.


.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 633 PM CDT Fri Sep 30 2016

VFR conditions this evening, and locations west of I-29 corridor are
expected to remain VFR throughout the period. MVFR ceilings will
work into northwest Iowa and parts of southwest Minnesota from the
east after 04z, with improvement back into the lower-end VFR range
after 18z Saturday. MVFR ceilings should work into the I-29 corridor
including KSUX/KFSD TAF locations by 10z-12z.




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